﻿using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;

namespace AdverseEventReportSystem.Utils {
	/// <summary>
	/// 验证码
	/// </summary>
	public class ValidateCode {
		/// <summary>
		/// 验证码的最大长度
		/// </summary>
		public int MaxLength {
			get { return 10; }
		}
		/// <summary>
		/// 验证码的最小长度
		/// </summary>
		public int MinLength {
			get { return 1; }
		}
		/// <summary>
		/// 生成验证码
		/// </summary>
		/// <param name="length">指定验证码的长度</param>
		/// <returns></returns>
		public string CreateValidateCode(int length) {
			int[] randMembers = new int[length];
			int[] validateNums = new int[length];
			string validateNumberStr = "";
			//生成起始序列值
			int seekSeek = unchecked((int)DateTime.Now.Ticks);
			Random seekRand = new Random(seekSeek);
			int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
			int[] seeks = new int[length];
			for (int i = 0; i < length; i++) {
				beginSeek += 10000;
				seeks[i] = beginSeek;
			}
			//生成随机数字
			for (int i = 0; i < length; i++) {
				Random rand = new Random(seeks[i]);
				int pownum = 1 * (int)Math.Pow(10, length);
				randMembers[i] = rand.Next(pownum, Int32.MaxValue);
			}
			//抽取随机数字
			for (int i = 0; i < length; i++) {
				string numStr = randMembers[i].ToString();
				int numLength = numStr.Length;
				Random rand = new Random();
				int numPosition = rand.Next(0, numLength - 1);
				validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
			}
			//生成验证码
			for (int i = 0; i < length; i++) {
				validateNumberStr += validateNums[i].ToString();
			}
			return validateNumberStr;
		}
		//C# MVC 升级版
		/// <summary>
		/// 创建验证码的图片
		/// </summary>
		/// <param name="containsPage">要输出到的page对象</param>
		/// <param name="validateNum">验证码</param>
		public byte[] CreateValidateGraphic(string validateCode) {
			Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
			Graphics g = Graphics.FromImage(image);
			try {
				//生成随机生成器
				Random random = new Random();
				//清空图片背景色
				g.Clear(Color.White);
				//画图片的干扰线
				for (int i = 0; i < 25; i++) {
					int x1 = random.Next(image.Width);
					int x2 = random.Next(image.Width);
					int y1 = random.Next(image.Height);
					int y2 = random.Next(image.Height);
					g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
				}
				Font font = new Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
				LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
																	Color.Blue, Color.DarkRed, 1.2f, true);
				g.DrawString(validateCode, font, brush, 3, 2);
				//画图片的前景干扰点
				for (int i = 0; i < 100; i++) {
					int x = random.Next(image.Width);
					int y = random.Next(image.Height);
					image.SetPixel(x, y, Color.FromArgb(random.Next()));
				}
				//画图片的边框线
				g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
				//保存图片数据
				MemoryStream stream = new MemoryStream();
				image.Save(stream, ImageFormat.Jpeg);
				//输出图片流
				return stream.ToArray();
			}
			finally {
				g.Dispose();
				image.Dispose();
			}
		}
		/// <summary>
		/// 得到验证码图片的长度
		/// </summary>
		/// <param name="validateNumLength">验证码的长度</param>
		/// <returns></returns>
		public static int GetImageWidth(int validateNumLength) {
			return (int)(validateNumLength * 12.0);
		}
		/// <summary>
		/// 得到验证码的高度
		/// </summary>
		/// <returns></returns>
		public static double GetImageHeight() {
			return 22.5;
		}
	}
}
